JP2018507378A - Magnetocaloric cascade and method for producing magnetocaloric cascade - Google Patents

Abstract

The present invention is a magnetocaloric cascade comprising successive magnetocaloric material layers having different Curie temperatures TC, the magnetocaloric material layer comprising a low temperature side outer layer, a high temperature side outer layer, and the low temperature side outer layer and the high temperature side Including at least three inner layers between the outer layers, and for each pair of adjacent magnetocaloric material layers of the magnetocaloric cascade, there is a respective crossing temperature, wherein both of the adjacent magnetocaloric material layers The entropy parameter mΔS takes the same intersection value, and the entropy parameter mΔS is defined as the product of the mass m of each magnetocaloric material layer and the isothermal magnetic entropy change ΔS during the magnetic phase transition of each magnetocaloric material layer -At least two of the inner layers have different masses m-the entropy parameter mΔS in all pairs of adjacent inner layers All intersection value, the magnetocaloric cascade all mean exactly equal to the intersection value in all pairs of adjacent inner layer, in the range of the width of ± 15%, about magnetocaloric cascade.

Description

  The present invention relates to a magnetocaloric cascade and a method for producing a magnetocaloric cascade. The invention further relates to a magnetocaloric regenerator, heat pump and heat-pumping method, including the use of a magnetocaloric cascade.

  With the progress of material research, magnetocaloric effect (MCE) has become known fluid circulation for industrial and commercial applications even at room temperature, such as refrigeration systems, cooling systems for ice production in the process industry, and air conditioner systems. It has emerged as an economically viable alternative to cooling methods. Another field of application of the magnetocaloric effect is in electromagnetic generators, ie the conversion of heat into electrical energy.

  The magnetocaloric effect occurs under the application of an external magnetic field to a suitable magnetocaloric material and ambient temperature near the Curie temperature. The applied external magnetic field aligns randomly aligned magnetic moments of the magnetocaloric material, thus causing a magnetic phase transition. This can also be explained as an induced increase in the Curie temperature of the material above ambient temperature. This magnetic phase transition means a decrease in magnetic entropy and leads to an increase in the entropy contribution of the magnetocaloric material crystal lattice due to phonon generation in the adiabatic process (thermal separation from ambient temperature). Thus, heating of the magnetocaloric material occurs as a result of applying an external magnetic field.

  In technical cooling applications, this additional heat is removed from the material by heat conduction to an ambient heat sink or heat medium in the mold. Water is an example of a heat medium used to remove heat from a magnetocaloric material. Subsequent removal of the external magnetic field can be explained as the Curie temperature drops below ambient temperature, and thus the magnetic moment returns to a random configuration. This causes an increase in magnetic entropy and a decrease in the entropy contribution of the magnetocaloric material's own crystal lattice, thus leading to cooling of the magnetocaloric material below ambient temperature in adiabatic process conditions. The process cycle described above, including magnetization and demagnetization, is typically performed periodically during device application.

  The above cooling effect can be achieved by designing the magnetocaloric material as a continuous layer with a decreasing Curie temperature, or in other words as a magnetocaloric cascade comprising two or more magnetocaloric material layers that are continuous for each decreasing Curie temperature. Can be increased. In such a magnetocaloric cascade, the first magnetocaloric material cools the second magnetocaloric material to a temperature close to the Curie temperature of the second magnetocaloric material, and any additional magnetocaloric content included in the cascade. The same applies to the material. In this way, the resulting cooling effect can be greatly increased compared to using a single magnetocaloric material.

  US 2004/0093877 A1 discloses a magnetocaloric material exhibiting a magnetocaloric effect at or near room temperature and a magnetic cooling device using such a magnetocaloric material. Different compositions of magnetocaloric materials result in different magnetocaloric materials exhibiting different Curie temperatures, ie different temperatures of the magnetic phase transition. The magnetocaloric material is placed in first and second regenerator beds that are exposed to a changing magnetic field. The regenerator forms the core of the magnetic cooling device. Similarly, WO 2004/068512 A1 and WO 2003/012801 describe magnetocaloric materials with different Curie temperatures obtained from a material system of a specific composition by varying the individual components or the relative amounts of the individual components. .

  US2011 / 0094243 consists of a cascade of at least three different magnetocaloric materials with different Curie temperatures, arranged sequentially for each rising or falling Curie temperature and isolated from each other by intermediate heat and / or electrical insulators A heat exchanger bed, wherein the difference in Curie temperature of adjacent magnetocaloric materials is 0.5-6K.

  US 8,104,293 B2 discloses a magnetocaloric cooling device comprising a plurality of thermally coupled magnetocaloric elements, one or more storage vessels containing a fluid medium, and two heat exchangers. The heat exchanger is thermally coupled to the magnetocaloric element and is thermally coupled to at least one storage vessel that transfers heat between the magnetocaloric element and the environment by a fluid medium.

  US2011 / 0173993A1 discloses a magnetocaloric element comprising at least two adjacent sets of magnetocaloric material arranged according to increasing Curie temperature. Magneto-caloric materials in the same set have the same Curie temperature. The magnetocaloric element further includes initiating means for creating a temperature gradient between two opposing hot and cold ends of the magnetocaloric element.

WO2014 / 115057A1 is a magnetocaloric cascade comprising at least three different magnetocaloric materials with different Curie temperatures, arranged in succession for each descending Curie temperature, for different magnetocaloric materials with different Curie temperatures. Both describe a magnetocaloric cascade that does not have a higher layer performance Lp than a magnetocaloric material with the highest Curie temperature. At least one of the different magnetocaloric materials having different Curie temperatures has a lower layer performance Lp than the magnetocaloric material having the highest Curie temperature. The layer performance Lp of a particular magnetocaloric material layer is the formula: Lp = m * dT _{ad, max} (where dT _{ad, max} is the specific magnetism when magnetized from low to high fields during the magnetocaloric cycle. Is the maximum adiabatic temperature change experienced by the calorimetric material, and m is calculated according to the mass of the particular magnetocaloric material included in the magnetocaloric cascade.

US2004 / 0093877 WO2004 / 068512 WO2003 / 012801 US2011 / 0094243 US8,104,293 US2011 / 0173993 WO2014 / 115057

According to a first aspect of the present invention, a magnetocaloric cascade is provided that includes at least three successive magnetocaloric material layers. The magnetocaloric cascade includes magnetocaloric material layer continuous with different Curie temperatures T _C, wherein
The magnetocaloric material layer includes a low temperature side outer layer, a high temperature side outer layer, and at least three inner layers between the low temperature side outer layer and the high temperature side outer layer;
-For each pair of adjacent magnetocaloric material layers of the magnetocaloric cascade, there is a respective intersection temperature, where the entropy parameter mΔS of both each adjacent magnetocaloric material layer takes the same intersection point value and the entropy parameter mΔS is defined as the product of the mass m of each magnetocaloric material layer and the isothermal magnetic entropy change ΔS during the magnetic phase transition of each magnetocaloric material layer,
-At least two of the inner layers have different masses m,
All intersection values of the entropy parameter mΔS in all pairs of adjacent inner layers are exactly equal to the average value of all intersection values in all pairs of adjacent inner layers of the magnetocaloric cascade or range of ± 15% width Is in. The magnetocaloric cascade may be abbreviated as a cascade in the following for brevity.

The parameter ΔS is a measure of the amount of isothermal magnetic entropy change obtained at the time of the magnetic phase transition of each magnetocaloric material layer. The amount of change in isothermal magnetic entropy can be determined by a technique known in the art, for example, estimation from isothermal magnetization data or estimation from isomagnetic field heat capacity data. The parameter ΔS is a function of temperature. The parameter ΔS is quantified, for example, in units of J / cm ³ / K, or more generally J / kg / K. For simplicity, even if an amount is used within the above context, the parameter is represented herein as ΔS rather than || ΔS ||. The parameter ΔS quantifies the characteristics of a given magnetocaloric material layer and thus constitutes a parameter that can be individually controlled for each layer by appropriate design of the magnetocaloric cascade. Usually, the maximum amount ΔS _maximum isothermal magnetic entropy change is obtained in the Curie temperature T _C of a given magnetocaloric material.

  The product of ΔS and mass for a given layer is referred to herein as an “entropy parameter” for ease of reference within this specification. However, this is not intended to define entropy. The entropy parameter can also be described as a mass-weighted isothermal magnetic entropy change during the magnetic phase transition. The entropy parameter is further shortened and is also referred to as mΔS.

The present invention recognizes the importance of the entropy parameter mΔS of the inner layer to improve the performance of the magnetocaloric cascade when transferring heat between the high temperature side and the low temperature side. The present invention further indicates that each actual magnetocaloric material has an individual temperature dependence of the entropy parameter, and typically exhibits an individual global maximum mΔS _maximum at each Curie temperature for each layer. Is recognized. The present invention demonstrates that the heat pumping capability of the magnetocaloric cascade can be improved by appropriately adjusting the entropy parameter mΔS throughout the inner layer of the magnetocaloric cascade. At least two of the inner layers have different masses m, and all intersection values of the entropy parameter mΔS in all pairs of adjacent inner layers are average values of all intersection values in all pairs of adjacent inner layers of the magnetocaloric cascade. The present invention provides a layer design of a magnetocaloric cascade that exhibits improved heat pumping capability compared to known layer designs, provided that it is exactly equal to or within a range of ± 15%.

  In the following, embodiments of the magnetocaloric cascade according to the first aspect of the invention will be described.

  In some embodiments, the margin of variation of the entropy parameter mΔS of all pairs of adjacent inner layers is based on the average of all intersection values of all pairs of adjacent inner layers of the magnetocaloric cascade. And smaller than ± 15%. In some embodiments, the width is ± 10%, and in other embodiments it is only ± 5%. The smaller the fluctuation range, the greater the performance improvement of the magnetocaloric cascade obtained when transferring heat between the high temperature side and the low temperature side.

  The magnetocaloric cascade can be realized by any suitable combination of magnetocaloric material layers. To achieve high heat pumping capability during cascade operation, the different magnetocaloric material layers of the cascade are as high as possible when combined, and in addition, at values that are the same or vary only within the aforementioned width range It is advantageous to show each material and each mass that results in an intersection value for the entropy parameter mΔS throughout the magnetocaloric cascade.

Due to different material properties, the temperature dependence of the entropy parameters shows a linearity in which their respective maximum amounts mΔS _max and width can differ greatly, eg determined as full width at half maximum (FWHM) relative to the maximum amount mΔS _max. . To properly select the magnetocaloric cascade material in this regard, take into account the Curie temperature difference ΔT _C (also referred to as the Curie temperature interval) between adjacent layers of the cascade. In general, the smaller the Curie temperature interval between two adjacent magnetocaloric layers of a cascade, the higher the intersection value of the entropy parameters of those two layers. Furthermore, the degree of breadth characterizing the function describing the temperature dependence of the entropy parameter mΔS constitutes a suitable parameter for influencing the amount of intersection value of the entropy parameters of adjacent magnetocaloric materials in a cascade design. For example, for a given Curie temperature interval, increasing the temperature-dependent full width at half maximum (FWHM) of the entropy parameter mΔS in at least one of the two adjacent layers by appropriate material selection, In general, the intersection value of the entropy parameters of the two adjacent magnetocaloric materials in the cascade will be high (for the sake of brevity, assume that the maximum amount mΔS _maximum does not change). The Curie temperature interval and FWHM cannot be determined solely by material selection from a given discrete set of materials. In some material systems, these parameters can be adjusted semi-continuously by selecting a suitable composition of the magnetocaloric material for each magnetocaloric layer. Several material systems are known that contain different constituent elements in the stoichiometric range. Exemplary material systems are MnFePAs, MnAsSb, and MnFePSiGe. Such a material system provides a substantially continuous range of Curie temperatures. A Curie temperature suitable for a particular magnetocaloric layer in a cascade design can be obtained by setting an appropriate stoichiometric composition of the constituent elements of the material in the material system. On the other hand, the temperature-dependent FWHM broadening of the entropy parameter can be achieved, for example, by mixing materials with slightly different stoichiometric compositions into a single layer, or with a magnetocaloric layer of equal thickness and homogeneous composition. Can be achieved by providing a magnetocaloric material layer with an underlying structure having a slightly different stoichiometric composition.

  In some embodiments of the cascade of the present invention, magnetocaloric layers with different material systems are used in the cascade. These embodiments provide particularly high design flexibility in implementing a cascade design according to the present invention. Magneto-caloric materials with differences in chemical or stoichiometric composition are subject to the same values of their material parameters related to realizing a magneto-caloric cascade in accordance with a given embodiment of the invention. Note that they are considered the same material in the context of this disclosure.

  In some embodiments, discussed in more detail below, neither the high temperature outer layer nor the low temperature outer layer meets the requirements of the intersection value applied to the inner layer in accordance with the present invention. For clarity of reference, these embodiments are referred to as the first group in the next paragraph. However, it should be noted that in other embodiments of the cascade, it is not only the inner layer that shows this particular design with respect to the intersection value of the entropy parameter mΔS. In addition, by a low temperature side outer layer pair (in the second group of embodiments) and its adjacent low temperature side inner layer, or (in the third group of embodiments) a high temperature side outer layer and its adjacent high temperature side inner layer The configured hot outer layer pair, or the hot and cold outer layer pair (in the fourth group of embodiments) is also exactly equal to the average of all intersection values in all pairs of adjacent inner layers of the magnetocaloric cascade. Or the intersection value of the entropy parameter mΔS within a range of ± 15%.

For the first to third group of embodiments mentioned in the previous paragraph, further operational improvements can be achieved by additional layer design measures. In the above context, as known per se, each pair of adjacent magnetocaloric layer, having each Curie temperature difference [Delta] T _C between the respective Curie temperatures. According to an additional design measures, the high-temperature side outer or cold-side outer layer, compared to either the inner layer of shows larger, the ratio mΔS _maximum / [Delta] T _C between the maximum value of entropy parameters mΔS and the Curie temperature difference [Delta] T _C . Magnetocaloric cascade by this type of embodiment, than any inner layer having the mΔS _maximum / [Delta] T _C of greater proportions, by providing a high-temperature-side outer or cold-side outer (or both), and a known magnetocaloric cascade In comparison, the performance of the magnetocaloric cascade in the heat pump magnetocaloric regenerator is further improved.

The parameter mΔS _max constitutes the maximum value of the entropy parameter mΔS. In other words, the parameter mΔS _max is a measure of the absolute maximum value of the isothermal magnetic entropy change obtained during the magnetic phase transition of each magnetocaloric material layer having a given mass m. For many magnetocaloric material, the maximum amount of the isothermal magnetic entropy change is obtained in the Curie temperature T _C of a given magnetocaloric material. The parameter mΔS _max is clearly defined for a given layer of a given mass and a given material composition by the characteristic linearity of the temperature dependence of ΔS. Thus, the magnetocaloric material has only a single ΔS _maximum . In general, different magnetocaloric materials have different values of ΔS _maximum . Changing the mass of the predetermined layer may be performed not only for adjusting the intersection value of the entropy parameter mΔS on the basis of the adjacent layer but also for adjusting the maximum value mΔS _maximum .

Parameter [Delta] T _C represents the difference between adjacent magnetocaloric material layer Curie temperature and one layer of a given layer. In this specification, each Curie temperature is meant as being measurable in the absence of an applied magnetic field. Curie temperature T _C is that the a parameter to quantify the characteristics of a given magnetocaloric layer, parameters [Delta] T _C is given continuous layer of a two-layer, i.e., a given layer of a cascade Describe the characteristics of the adjacent magnetocaloric layer. Since it is such, parameters [Delta] T _C is one that spans a given individual layer. Parameter [Delta] T _C is related to the order of the design layer of magnetocaloric cascade.

For the definition of [Delta] T _C, for simplicity, even if a certain amount is meant, the parameter, rather than || [Delta] T C _||, it should be noted that represented by [Delta] T _C. Further, the above definition of [Delta] T _C, sometimes ambiguity at a glance are seen. If the inner layer of the cascade, the inner layer of one layer, one on each side, for having adjacent layers of two layers, two different values of principle parameters [Delta] T _C can be determined. However, when comparing the parameter values of [Delta] T _C in the cascade, since there is a sequence determination of [Delta] T _C along either of the two possible directions along the cascade, there is no ambiguity as described above. The order of determination is preferably according to the direction of heat flow through the cascade, depending on the given application (cooling or heating). In either case, the set of values of [Delta] T _C throughout a given cascade is the same regardless of the order of determination. As for the high temperature side layer and the low temperature side layer, the high temperature side layer and the low temperature side layer constitute an outer layer of the cascade, so that there is naturally only one adjacent layer.

In comparison with the inner layer of the cascade in embodiments, when the maximum parameters mΔS _maximum / [Delta] T _C in the high temperature-side layer or the low-temperature-side layer of the cascade, as further illustrated in the following examples, the entire cascade performance further Improve. The effect obtained can also be described as a cascade reinforcement at each outer end facing the hot or cold side of the heat pump. The relatively small differences in mΔS _up / [Delta] T _C, in either a hot side or the cold side outer as compared with the inner layer, improvement has already been achieved. The advantageous effect of this embodiment on the heat pumping capability of the magnetocaloric cascade as compared to the known cascade design increases especially as the temperature range between the hot and cold sides of the cascade increases. This temperature range usually finds at least approximately a corresponding Curie temperature difference between the high temperature side outer layer and the low temperature side outer layer. Compared to a conventional design for a given temperature range, the above embodiments provide heat pumping with improved performance, even at temperature differences significantly greater than the normal temperature range.

Hot side outer layer or the low-temperature side outer layer, compared to either the inner layer of preferably exhibits a ratio mΔS _maximum / [Delta] T _C of at least 1% greater amount. In other embodiments, Emuderutaesu _maximum / [Delta] T _C is the high temperature side outer or cold-side outer layer by at least 5% greater than any of the inner layer at least one layer. In another embodiment, the parameter mΔS _maximum / [Delta] T _C is the high temperature side outer or cold-side outer layer, at least 10% greater than any of the inner layer at least one layer. In one embodiment, the high temperature-side outer or cold-side outer layer, compared to either the inner layer of, shows the ratio mΔS _maximum / [Delta] T _C of at least 20% greater amount. In yet another embodiment, the high temperature-side outer or cold-side outer layer, represents the ratio mΔS _maximum / [Delta] T _C of 150% or less of the amount, in other embodiments, compared to either the inner layer of the following 100% Indicates the size. Improvement of the heat pumping capacity is the ratio mΔS _maximum / [Delta] T _C increases substantially in proportion to the increase of the higher becomes percentage than the inner layer at a high temperature side outer or cold-side outer layer. However, to increase the ratio by selecting a magnetocaloric material with a higher entropy parameter maximum ΔS _maximum , the ΔS of the material selected to achieve a high intersection value relative to a given adjacent layer. It is necessary to pay attention to the temperature-dependent line width (FWHM).

In three alternative embodiments of the magnetocaloric cascade, the aforementioned enhancement measures for the outer layer of the cascade relate to a) only the high temperature side outer layer, b) only the low temperature side outer layer, or c) both the high temperature side outer layer and the low temperature side outer layer. Therefore, the high temperature-side outer or cold-side outer layer, compared to either the inner layer of, when stating that exhibit greater ratios mΔS _up / [Delta] T _C, the term "or" is intended to include all three options mentioned Should be understood.

Thus, in some embodiments of the magnetocaloric cascade representing the choices mentioned third, high-temperature-side outer layer and the low-temperature side outer layer indicates the same value of the ratio mΔS _up / [Delta] T _C. This achieves a particularly great improvement with respect to the performance of the magnetocaloric cascade. In similar embodiments, one of the high temperature side and low temperature side outer layer has a ratio mΔS _maximum / [Delta] T _C higher amount than the other. In some of these other embodiments, one of the high temperature side and low temperature side outer layer has a ratio mΔS _maximum / [Delta] T _C higher than any of the inner layer at least one layer of an amount.

The maximum amount [Delta] T C of entropy parameters _{Emuderutaesu,} i.e., can be used in combination alone or mutually different measures to adjust the Emuderutaesu _maximum / [Delta] T _C, to achieve the design of a preferred embodiment of the cascade.

One such measure that has been implemented in some embodiments is to increase the amount of ΔS _maximum compared to any of the inner layers. The ΔS _maximum variation can be achieved, for example, by appropriate material selection, which naturally takes into account the requirements of a given application with respect to the Curie temperature. The high temperature side outer layer or the low temperature side outer layer in some variants of this type of embodiment exhibits an amount of ΔS _maximum that is at least 2% greater than either of the inner layers. Greater effects are achieved with other variants having a ΔS _maximum amount of at least 10% greater than either the inner layer, either in the high temperature side outer layer or in the low temperature side outer layer. The upper limit of the rising ΔS _maximum in the high temperature side outer layer or the low temperature side outer layer compared to the inner layer is about 50% compared to any of the inner layers.

According to another measure that may be used in combination with or the measures in the alternative, the high-temperature side outer or cold-side outer layer, compared to either the inner layer of shows [Delta] T _C of smaller amounts. As is known per se, in a magnetocaloric material system, variations in ΔT _c are, for example, stoichiometric, ie in the material composition within a given material system for designing a given layer of the cascade. It can be achieved by adjusting different fractions of the constituent elements. In a further embodiment of the magnetocaloric cascade hot side layer or the low temperature side layer, compared to either of the inner layer at least one layer, it shows a [Delta] T _C of at least 0.2% smaller amounts. In another embodiment of the magnetocaloric cascade hot side layer or the low temperature side layer, compared to either of the inner layer at least one layer, it shows a [Delta] T _C of at least 5% smaller amounts. However, based on the lower limit of the preferred amount of [Delta] T _C, the high temperature-side layer or the low-temperature-side layer, or 0.25 K, preferably 0.5K or more, it is preferable to indicate the amount of [Delta] T _C.

To influence the intersection value of the entropy parameter ΔS, another design parameter used in some embodiments is a temperature-dependent line width, eg, full width at half quantified in units of K. the maximum) amount (ΔS _maximum ). A combination of different magnetocaloric layers in at least one of the layers may be used to increase the large line width and thus increase the intersection value of a given pair of adjacent magnetocaloric layers. In some such embodiments, continuous sublayers, preferably those that do not reduce the maximum amount of mixing ΔS _max as compared to a single layer, can be used.

  In such an embodiment suitable for further increasing the strength of at least one of the outer layers, the hot outer layer or the cold outer layer or both are at least two hot sublayers or cold sides, respectively. Contains successive lower layers of lower layers. In this way, grading of the Curie temperature in each outer layer can be obtained, and the heat pumping effect in each outer layer is further improved.

As already mentioned, parameters mass, each of ΔS _maximum and [Delta] T _C, in order to adjust the intersection values, and / or the high temperature side or low-side outer layer and / or its adjacent layer of the cascade of mΔS _up / [Delta] T _C To adjust the maximum amount, any of the layers may be changed alone or in combination.

  A magnetocaloric material system in which materials for use in any of the magnetocaloric cascade embodiments can be selected according to the requirements of the embodiments described herein is, for example, WO2014 / 115057A1, page 11, lines 26-14. It is disclosed on page 31. The entire published WO2014 / 115057A1 is hereby incorporated by reference.

  According to a second aspect of the present invention, there is provided a magnetocaloric regenerator comprising a magnetocaloric cascade according to any one of the first aspect of the present invention or an embodiment thereof.

  The magnetocaloric regenerator shares the advantages of the magnetocaloric cascade according to the first aspect of the invention.

  The magnetocaloric regenerator can be implemented in many different embodiments. Some of these different embodiments include the first aspect of the magnetocaloric cascade in different shapes. In some embodiments, a planar shape is used. In other embodiments, the magnetocaloric cascade comprises one or more channels or a plurality of microchannels that extend through the magnetocaloric cascade to accommodate a heat transfer fluid. The magnetocaloric generator may include magnetocaloric material layers with different material shapes. The magnetocaloric material layer is, in some embodiments, constituted by a solid material layer or a porous magnetocaloric material layer. In another embodiment, the magnetocaloric material layer is composed of magnetocaloric particles, and the magnetocaloric particle is a compound material having a spherical shape, an aspherical shape such as a disc shape, or an irregular shape in different embodiments. The spherical particles of different embodiments have a particle size of 50-500 μm, and in some embodiments, a particle size of about 100 μm. The particle layer is generally formed using a binding material under pressure. In a currently preferred embodiment, the regenerator comprises a packed bed of particle beds.

  According to a third aspect of the present invention, there is provided a heat pump comprising a magnetocaloric regenerator according to any one of the second aspect of the present invention or an embodiment thereof. The heat pump shares the advantages of the magnetocaloric regenerator according to the second aspect of the present invention.

  Hereinafter, an embodiment of a heat pump will be described.

  The heat pump embodiment is suitably configured to cyclically perform a pumping sequence that includes a temperature rise and a temperature drop of the heat pump operating body.

  In a further preferred embodiment, the heat pump includes a high temperature side interface that exchanges heat with the high temperature side outer layer, a low temperature side interface that exchanges heat with the low temperature side outer layer, and the high temperature side interface and the low temperature side interface via a magnetocaloric cascade. A heat transfer system configured to generate a flow of heat transfer fluid therebetween, wherein the hot outer layer Curie temperature is selected to be higher than the hot interface temperature during heat pump operation The Curie temperature of the low temperature side outer layer is selected to be lower than the temperature of the low temperature side interface during the heat pump operation. For example, in cooling applications, the low temperature side interface is configured to be in thermal contact with the object to be cooled, and the high temperature side interface is configured to be in thermal contact with the heat sink.

According to a fourth aspect of the present invention, a method for producing a magnetocaloric cascade is provided. The method
- different a Curie temperature T _C to produce different consecutive magnetocaloric material layer having a step, the magnetocaloric material layer, the low-temperature side outer, high-temperature-side outer layer and between the high temperature side outer and the low temperature side outer Including at least three inner layers in between;
-Producing at least two of the inner layers having different masses m,
-For each pair of adjacent magnetocaloric material layers of the magnetocaloric cascade, there is a respective crossing temperature, where the pumping capacity entropy parameter mΔS of both each adjacent magnetocaloric material layer takes the same crossing point value and entropy The parameter mΔS is defined as the product of the mass m of each magnetocaloric material layer and the isothermal magnetic entropy change ΔS during the magnetic phase transition of each magnetocaloric material layer;
Furthermore,
All intersection values of the entropy parameter mΔS in all pairs of adjacent inner layers are exactly equal to the average value of all intersection values in all pairs of adjacent inner layers of the magnetocaloric cascade or range of ± 15% width Which includes a process.

  The method according to the fourth aspect of the present invention achieves the above advantages in the context of the magnetocaloric cascade according to the first aspect of the present invention. Embodiments of the method include the step of manufacturing a cascade so as to further include additional features of the embodiments described in the context of the first aspect of the invention.

In one embodiment of the method, each of the pair of adjacent magnetocaloric layers, having respective Curie temperature difference [Delta] T _C between each Curie temperature, compared to either the inner layer of larger, maximum entropy parameters mΔS as shown the ratio mΔS _maximum / [Delta] T _C between the value and the Curie temperature difference [Delta] T _C, the high temperature-side outer or cold-side outer layer is produced.

According to the fifth aspect of the present invention, the heat pumping method comprises:
-Performing a heat pumping sequence using a magnetocaloric regenerator comprising a magnetocaloric cascade according to the first aspect of the invention or any one of its embodiments.

  Hereinafter, an embodiment of the heat pumping method will be described.

  In one embodiment, the pumping sequence includes a temperature increase of the magnetocaloric cascade performed in heat exchange with the heat sink. The pumping sequence is performed using a magnetocaloric cascade having a hot outer layer that is a magnetocaloric material layer having a Curie temperature 0.5-5K above the heat sink temperature.

  Further embodiments are set forth in the enclosed claims.

  In the following, further embodiments will be described with reference to the enclosed drawings.

FIG. 1 shows a plot of entropy S as a function of temperature T plotted in linear units (joules / kelvin) and linear units Kelvin for a magnetocaloric material layer. The curve shown in the figure is also referred to as an ST curve. FIG. 1 is merely schematic and is intended only to explain the following. The magnetocaloric material layer exhibits different ST curves under application of different amounts of magnetic field. Two exemplary curves A and B show the case where H = 0 (no magnetic field applied) and H ≠ 0 (a specific amount of magnetic field applied). It can be seen that the ST curve for H = 0 is at a higher entropy level due to the greater contribution of magnetic entropy to the total entropy of the magnetocaloric material layer shown. The crystal lattice and the electrons of the magnetocaloric material of the layer provide a further contribution to the entropy S. Under application of a magnetic field strong enough to cause a phase transition of the magnetocaloric material layer that leads to the orientation of the total magnetic moment along the direction of the magnetic field vector, the magnetic entropy at a given temperature is reduced by a _maximum amount ΔS. This causes a temperature rise. The maximum temperature rise in the adiabatic process is ΔT _{ad, maximum} , and occurs at a temperature different from the temperature at which the ΔS _maximum is observed as shown in FIG.

  Hereinafter, FIGS. 2 to 4 will be referred to in parallel. FIG. 2 illustrates one embodiment of a magnetocaloric cascade 10 that is used as a magnetocaloric regenerator and is therefore used as the operating body of a cooling device for transferring heat in the direction indicated by arrow 11. FIG. 3 is an explanatory diagram of the temperature dependence of the isothermal magnetic entropy change ΔS during the magnetic phase transition of each magnetocaloric material layer in the cascade of FIG. FIG. 4 shows an explanatory diagram of the temperature dependence of the mass-weighted isothermal magnetic entropy change (ie, entropy parameter) during the magnetic phase transition of each magnetocaloric material layer in the cascade of FIG.

  Cascade 10 is composed of 12-20 continuous magnetocaloric material layers. In particular, in this embodiment, the cascade has a low temperature side outer layer 12, followed by a plurality of magnetocaloric inner layers, of which inner layers 14, 16 and 18 are provided. Further, the cascade has a hot outer layer 20. The layer pair (12, 14) constituted by the low temperature side outer layer 12 and the adjacent inner layer 14 is also referred to as a low temperature side outer layer pair in this specification. The layer pair (18, 20) constituted by the high temperature side outer layer 20 and the adjacent inner layer 18 is also referred to as a high temperature side outer layer pair in this specification.

  The 10-layer continuous magnetocaloric cascade has the following specific features illustrated by FIGS. First, FIG. 3 shows a schematic diagram of the temperature dependence of the mass-weighted isothermal magnetic entropy change ΔS during the magnetic phase transition of each magnetocaloric material layer of the cascade according to the prior art. The magnetocaloric cascade underlying the diagram of FIG. 3 has five magnetocaloric material layers similar to the structure of FIG. The magnetocaloric layer is referred to as 12'-20 '. However, the magnetocaloric cascade referred to in FIG. 3 is a structure according to the prior art, as will be apparent from the following description.

Different magnetocaloric material layer 12 to 20 have the same mass and different Curie temperatures T _C, 3, from the viewpoint of the reference label of the corresponding layer, 'from the hot side outer layer 20' cold side outer 12 to The values increase continuously and are labeled T _C ⁽¹²⁾ , T _C ⁽¹⁴⁾ , T _C ⁽¹⁶⁾ , T _C ^(18), and T _C ⁽²⁰⁾ . For each pair of adjacent magnetocaloric material layers of the magnetocaloric cascade, ie for the layer pairs (12, 14), (14, 16), (16, 18) and (18, 20), each crossing temperature T1 ′, T2 ′, T3 ′ and T4 ′ are present, where the product mΔS of the layer mass and the isothermal magnetic entropy change ΔS in the magnetic phase transition of each magnetocaloric material layer is the same in both adjacent magnetocaloric material layers. is there. Corresponding intersections are labeled as C1 ′, C2 ′, C3 ′ and C4 ′. The average intersection value mΔS ′ _average of all pairs of adjacent inner layers, ie layer pairs (14, 16) and (16, 18), can be calculated and is shown in the graph of FIG. As FIG. 3 shows, the values of mΔS at the intersections C1 ′, C2 ′, C3 ′ and C4 ′ are different. In particular, the intersection value of C2 ′ and C3 ′ mΔS for inner layer pairs (14, 16) and (16, 18) is the average mΔS ′ _average of all intersection values in all pairs of adjacent inner layers of the magnetocaloric cascade. Is within ± 15% of the width. The upper and lower limits of the width from the average intersection value mΔS ′ _average are labeled in FIG. 3 as mΔs ′ _average + 15% and mΔs ′ _average− 15%, which are mΔs ′ _average + 0.15 * mΔs ′ _average. And mΔs ′ _average −0.15 * mΔs ′ _average . Note that this illustration is schematic and therefore may not show values to scale.

In contrast, FIG. 4 shows an illustration of the temperature dependence of the mass-weighted isothermal magnetic entropy change (ie, entropy parameter) during the magnetic phase transition of each magnetocaloric material layer of the cascade of FIG. The Curie temperatures T _C ⁽¹²⁾ , T _C ⁽¹⁴⁾ , T _C ⁽¹⁶⁾ , T _C ⁽¹⁸⁾ and T _C ⁽²⁰⁾ of each layer are the same as those of the prior art cascade referenced in FIG. It is assumed that However, this is simply for the sake of brevity. As shown in FIG. 4 for the embodiment of FIG. 2, the materials and mass of the different layers 12-20 of the cascade 10 are individually adjusted to form an embodiment of the present invention. In other words, in the cascade 10, at least two of the magnetocaloric material layers have different masses m. With suitable material selection and layer mass design, the same intersection values C1, C2, C3 and C4 of the mass weighted entropy change, ie the entropy parameter mΔS defined above, are obtained. More specifically, the entropy parameter mΔS, which is defined as the product of the mass m of the individual magnetocaloric material layer and its isothermal magnetic entropy change ΔS at the time of the magnetic phase transition of each magnetocaloric material layer, is the crossing temperature T1, It is the same at T2, and T3 and T4, and is different from the cross temperatures T1 ′, T2 ′, T3 ′ and T4 ′. Therefore, in this embodiment, all the intersection values C1, C2, C3 and C4 of the entropy parameter mΔS throughout the magnetocaloric cascade are completely equal. In other embodiments, these intersection values are equal within a range of ± 15% relative to the average mΔS _average of all intersection values in all pairs of adjacent inner layers of the magnetocaloric cascade.

A conspicuous feature of this embodiment is that all the intersection values C1, C2, C3 and C4 of the entropy parameter mΔS based on the adjacent magnetocaloric layer are actually the same. According to the present invention, this is not a requirement, and the present invention shows that all inner layers are, with respect to adjacent inner layers, exactly equal to the average mΔS _average of all intersection values of all pairs of adjacent inner layers of the magnetocaloric cascade. It is only required to have an intersection value for the entropy parameter mΔS, which is in the range of ± 15% width. As further shown below, a further embodiment according to the present invention has a hot side and a cold side outer layer designed to show an intersection value outside the width from the mΔS _average described above.

  As a further prominent feature of this embodiment, the maximum amount of mΔS is equal in all layers. However, this is not a requirement.

  Based on the described design, the cascade 10 has achieved particularly high performance in heat pumping applications.

FIGS. 5 and 6 illustrate mass-weighted isothermal magnetic entropy changes (i.e., during a magnetic phase transition in two adjacent magnetocaloric material layers 52, 54 and 62, 64 according to two different embodiments of a magnetocaloric cascade according to the present invention). It is explanatory drawing of the temperature dependence of an entropy parameter). The magnetocaloric cascade referred to in FIGS. 5 and 6 comprises a plurality of magnetocaloric layers. In particular, at least three inner layers are provided that comply with the stated requirements for intersection equality or width relative to the _average mΔS _average of all intersection values of the inner layer pairs. However, such information about the further layers of the cascade is omitted in FIGS. 5 and 6 for reasons of brevity. Two adjacent magnetocaloric material layers 52, 54 and 62, 64 constitute each outer layer pair as shown. In other words, the layers 52 and 62 are high temperature side or low temperature side outer layers, and are referred to as outer layers for short in the following. Each adjacent layer 54 and 64 constitutes an inner layer in terms of claims.

The outer layers 52 and 62 of both embodiments are reinforced in these two embodiments of the invention, as described below. 5 embodiment, the outer layer 52, as compared with the adjacent inner layer 54, the maximum amount mΔS _maximum entropy parameters mΔS becomes higher. This property of the outer layer 52 can be achieved by a suitable material selection or a suitable setting of the mass of the outer layer 52. Material and / or mass of the selected adjacent inner layer 54 the maximum amount mΔS _maximum entropy parameter mΔS compared becomes higher as the outer layer 52, the temperature dependence of the full width at half maximum of mΔS _maximum preferred actual amount and entropy parameters mΔS Assuming that there is a tendency to increase the intersection value C5 of mΔS of the two curves shown in FIG. In some embodiments that implement the situation of FIG. 5, the intersection value C5 is an external value that is ± 15% wide relative to the _average mΔS _average of all intersection values in all pairs of adjacent inner layers of the magnetocaloric cascade. It is in. In other embodiments, the intersection value C5 falls within this width, even if it is fully equal.

In the embodiment of FIG. 6, the outer layer 62, as compared with the adjacent inner layer 64, the maximum amount mΔS _maximum entropy parameters mΔS are the same. However, the material of the layers, their Curie temperature interval [Delta] T _C is selected to be small compared to the embodiment of FIG. This also leads to an increase in the intersection value C6 of the entropy parameter mΔS based on the highest maximum value individually in the entire cascade. The selection of the Curie temperature difference between the outer layer 62 and the adjacent inner layer assumes that the intersection value C6 of mΔS of the two curves shown in FIG. 5 is assumed, assuming a preferred full width at half maximum of the temperature dependence of the entropy parameter mΔS. There is a tendency to increase. In some embodiments that implement the situation of FIG. 6, the intersection value C6 is an external value with a width of ± 15% relative to the average value mΔS _average of all intersection values in all pairs of adjacent inner layers of the magnetocaloric cascade. It is in. In other embodiments, the intersection value C6 falls within this width, even if it meets full equality.

  Both measures described achieve an improvement in heat pumping performance.

  In the following, further embodiments of the cascade will be considered with reference to FIGS.

FIGS. 7-14 show Engelbrecht: “A Numeric Model of an Active Magnetic Regenerator Refrigeration System”, http: // digital. library. wsc. FIG. 6 shows the results of a virtual experiment performed using a physical model similar to that described in edu / 1793/7596. A one-dimensional model was used. The total mass of the magnetocaloric material of the cascade was 0.025 kg. The transfer volume per blow was 4 × 10 ⁻⁶ m ³ .

  In the virtual experiment, a reference cascade was used to demonstrate the beneficial effect on the pumping capability achieved by this embodiment. In particular, in the reference cascade shown in FIGS. 7 and 11, all magnetocaloric material layers have the same mass.

Example 1:
The cooling capacity was quantified for a reference cascade according to FIG. 7, which was not in accordance with the invention and was used for comparison purposes only. The reference cascade has the following characteristics: The reference cascade includes six consecutive magnetocaloric layers 1′-6 ′ that exhibit a Curie temperature corresponding to the maximum of the curve shown in FIG. These layers have the same reference mass and the total mass of the total magnetocaloric layer is 0.025 kg. The transfer volume per blow is 4 × 10 ⁻⁶ m ³ . For the purpose of simplifying the graphical display only, the mass was assumed to be 1 kg per layer in determining the curves of FIGS. In the actual capacity calculation shown in FIGS. 9 and 10, the actual mass was used.

  The intersection of the entropy parameter curves as a function of temperature is as specified in Table 1.

  The deviation values shown in Table 1 were calculated based on the average value (9.17 J / K) of the intersections C1 'to C5'.

  In comparison, the cascade represented in FIG. 8 is based on the same magnetocaloric material in the different layers 1-6. However, some of the layers of the cascade of FIG. 8 have different masses than the corresponding layers of the reference cascade of FIG. The relative mass is shown in Table 2, where mass 1 corresponds to 0.0025 kg divided by the number of layers (ie 6). Each layer is numbered as layer 1 -layer 6, which are layer 1 ′ (low temperature side outer layer) to layer 6 ′ (high temperature side outer layer) of FIG. 7 and layer 1 of the embodiment of FIG. It means (low temperature side outer layer) to layer 6 (high temperature side outer layer).

  As shown in Table 2, due to the change in the mass of layers 1, 2, 4, 5 and 6 in the embodiment of FIG. 8 compared to the reference cascade of FIG. was gotten.

  The deviation values shown in Table 1 were calculated based on the average value (8.62 J / K) of the intersections C1 to C5.

  The cooling capacity was quantified for the reference cascade of FIG. 7 and the embodiment of the cascade of the present invention of FIG. FIG. 9 is a diagram showing the cooling capacity (CP, unit: watts) of the cascade of FIGS. 7 and 8 as a function of the temperature range (TS) (unit: Kelvin) between the high temperature side outer layer and the low temperature side outer layer. is there. The different symbols used represent different cascades, the CP values obtained for the embodiment of FIG. 8 are represented by squares, and the CP values obtained for the reference cascade (FIG. 7) are represented by diamonds. Yes. The cooling capacity of the embodiment of FIG. 8 is clearly higher than that of the reference cascade of FIG. 7 for all temperature ranges. FIG. 10 shows the operating temperature of the high temperature side interface of the cascade of 23.9 ° C. in the temperature range TS of 0-20K, for different temperature ranges TS (unit: K), ie different operating temperatures at the low temperature side interface of the cascade. FIG. 8 shows the cooling capacity improvement (ICP) (unit:%) of the embodiment of FIG. 8 in relation to the cooling capacity of the reference cascade of FIG. 7 above. The temperature values used to determine each temperature range are acquired at the hot and cold entry points entering the cascade.

  9 and 10 show that the cooling capacity of the magnetocaloric cascade of the embodiment of FIG. 8 is greatly improved over the entire temperature range TS of 0 to 20 K compared to the reference cascade of FIG. It clearly shows that. This improvement is generally the same over the entire temperature range.

Example 2:
Cooling capacity was quantified for a reference cascade according to FIG. 11 that was not in accordance with the present invention and was used for comparison purposes only. The reference cascade has the following characteristics: The reference cascade includes five consecutive magnetocaloric layers 1′-5 ′ showing the Curie temperature corresponding to the maximum of the curve shown in FIG. These layers have the same reference mass and the total mass of all five magnetocaloric layers is 0.025 kg. The transfer volume per blow is 4 × 10 ⁻⁶ m ³ . As described above, the mass was assumed to be 1 kg per layer in determining the curves of FIGS. 11 and 12 for the purpose of simplifying the graph display. The actual mass of 0.025 kg divided by the number of layers (ie 5) was used for the cooling capacity calculations shown in FIGS.

  The intersection of the curves of the reference cascade entropy parameters as a function of temperature is as specified in Table 4.

  The deviation values shown in Table 1 were calculated based on the average value (11.21 J / K) of the intersections C1 'to C4'.

  In comparison, the cascade represented in FIG. 12 is based on the same material in the different layers 1-5. However, some of the layers of the cascade of FIG. 12 have different masses than the corresponding layers of the reference cascade of FIG. The relative mass is shown in Table 2, where mass 1 corresponds to 0.0025 kg. Each layer is numbered as layer 1 -layer 5, which are layer 1 ′ (low temperature side outer layer) to layer 5 ′ (high temperature side outer layer) of FIG. 11 and layer 1 of the embodiment of FIG. It means (low temperature side outer layer) to layer 5 (high temperature side outer layer).

  As shown in Table 2, the following intersection values were obtained in the embodiment of FIG.

  The deviation values shown in Table 1 were calculated based on the average value (11.67 J / K) of the intersections C1 to C4.

  The cooling capacity was quantified for the reference cascade of FIG. 11 and the embodiment of the cascade of the present invention of FIG. FIG. 13 is a diagram showing the cooling capacity (CP, unit: watts) of the cascade of FIGS. 11 and 12 as a function of the temperature range (TS) (unit: Kelvin) between the high temperature side outer layer and the low temperature side outer layer. is there. The different symbols used represent different cascades, the CP values obtained for the embodiment of FIG. 12 are represented by squares, and the CP values obtained for the reference cascade (FIG. 11) are represented by diamonds. Yes. The cooling capacity of the embodiment of FIG. 12 is clearly higher than that of the reference cascade of FIG. 11 for all temperature ranges up to 6K. FIG. 14 shows the operating temperature of the high temperature side interface of the cascade of 9.8 ° C. in the temperature range TS of 0 to 8K, for different operating temperature ranges TS (unit: K), ie different operating temperatures at the low temperature side interface of the cascade. FIG. 12 shows the cooling capacity improvement (ICP) (unit:%) of the embodiment of FIG. 12 in relation to the cooling capacity of the reference cascade described above (FIG. 11). The temperature values used to determine each temperature range are acquired at the hot and cold entry points entering the cascade.

  FIGS. 13 and 14 show that the cooling capacity of the magnetocaloric cascade of the embodiment of FIG. 8 is greatly improved in the temperature range TS of 0 to 6 K compared to the reference cascade of FIG. Clearly shows. This improvement is the same over the entire temperature range of this range.

  For cascades with two (or more) outer layers on one or both sides modified to increase the mass per layer or reduce the Curie temperature interval, the results are similar.

The schematic diagram showing the difference in the temperature dependence of magnetic entropy in the case where the magnetocaloric material is exposed to the magnetic field in the vicinity of the Curie temperature and the case where it is not exposed is shown. 2 illustrates an embodiment of a magnetocaloric cascade. FIG. 9 shows an explanatory diagram of the temperature dependence of isothermal magnetic entropy change ΔS during the magnetic phase transition of each magnetocaloric material layer of the cascade according to the prior art. FIG. 3 is an explanatory diagram of temperature dependence of mass-weighted isothermal magnetic entropy change (that is, entropy parameter) at the time of magnetic phase transition of each magnetocaloric material layer in the cascade of FIG. 2. FIG. 6 is an illustration of the temperature dependence of a mass-weighted isothermal magnetic entropy change (ie, entropy parameter) during a magnetic phase transition of two adjacent magnetocaloric material layers according to one of two different embodiments of the magnetocaloric cascade. FIG. 4 is an illustration of the temperature dependence of mass-weighted isothermal magnetic entropy change (ie, entropy parameter) during magnetic phase transition of two adjacent magnetocaloric material layers according to the other of two different embodiments of the magnetocaloric cascade. FIG. 4 shows an illustration of the temperature dependence of mass-weighted isothermal magnetic entropy change (ie entropy parameter) during a magnetic phase transition for each magnetocaloric material layer of a reference cascade used as an exemplary embodiment of a cascade not according to the invention. . For comparison, an explanatory diagram of the temperature dependence of the mass-weighted isothermal magnetic entropy change (that is, the entropy parameter) during the magnetic phase transition of each magnetocaloric material layer of the embodiment according to the present invention is shown. FIG. 9 is a diagram showing the cooling capacity (CP, unit: watts) of the cascade of FIGS. 7 and 8 as a function of the temperature range (TS) (unit: Kelvin) between the high temperature side outer layer and the low temperature side outer layer. FIG. 9 illustrates a cooling capability improvement (abbreviated as ICP) for the embodiment of the magnetocaloric cascade of FIG. 8 compared to the reference cascade of FIG. 7 for different temperature ranges between the high temperature side temperature and the low temperature side temperature. FIG. 4 shows an illustration of the temperature dependence of mass-weighted isothermal magnetic entropy change (ie entropy parameter) during a magnetic phase transition for each magnetocaloric material layer of a reference cascade used as an exemplary embodiment of a cascade not according to the invention. . For comparison with FIG. 11, an explanatory diagram of the temperature dependence of the mass-weighted isothermal magnetic entropy change (ie, entropy parameter) at the time of the magnetic phase transition of each magnetocaloric material layer of the embodiment according to the present invention is shown. FIG. 13 is a diagram showing the cooling capacity (CP, unit: watt) of the cascade of FIGS. 11 and 12 as a function of the temperature range (TS) (unit: Kelvin) between the high temperature side outer layer and the low temperature side outer layer. FIG. 13 illustrates a cooling capability improvement (abbreviated ICP) for the embodiment of the magnetocaloric cascade of FIG. 12 compared to the reference cascade of FIG. 11 for different temperature ranges between the high temperature side temperature and the low temperature side temperature.

Claims (15)

A magnetocaloric cascade containing magnetocaloric material layer continuous with different Curie temperatures T _C,
The magnetocaloric material layer includes a low temperature side outer layer, a high temperature side outer layer, and at least three inner layers between the low temperature side outer layer and the high temperature side outer layer;
-For each pair of adjacent magnetocaloric material layers of the magnetocaloric cascade, there is a respective crossing temperature, where the entropy parameter mΔS of both adjacent magnetocaloric material layers takes the same crossing point value and the entropy parameter mΔS Is defined as the product of the mass m of each magnetocaloric material layer and the isothermal magnetic entropy change ΔS during the magnetic phase transition of each magnetocaloric material layer,
-At least two of the inner layers have different masses m,
All intersection values of the entropy parameter mΔS in all pairs of adjacent inner layers are exactly equal to the average value of all intersection values in all pairs of adjacent inner layers of the magnetocaloric cascade or range of ± 15% width In
Magnetocaloric cascade.   All intersection values of the entropy parameter mΔS in all pairs of adjacent inner layers are exactly equal to the average value of all intersection values in all pairs of adjacent inner layers of the magnetocaloric cascade or within a range of ± 10% The magnetocaloric cascade according to claim 1, wherein   The low temperature side outer layer pair constituted by the low temperature side outer layer and the adjacent low temperature side inner layer, or the high temperature side outer layer pair constituted by the high temperature side outer layer and the adjacent high temperature side inner layer, or the high temperature side outer layer and the low temperature side outer layer. Wherein the pair of is indicative of an intersection value of the entropy parameter mΔS that is exactly equal to the average value of all the intersection values in all pairs of adjacent inner layers of the magnetocaloric cascade or within a range of ± 15%. 2. The magnetocaloric cascade according to 1. - wherein each pair of adjacent magnetocaloric layer of magnetocaloric cascade has a respective Curie temperature difference [Delta] T _C between their respective Curie temperatures, further,
- the hot side outer layer or the low-temperature side outer layer or both the high temperature side outer layer and the low temperature side outer layer, compared to either the inner layer, the larger the maximum value of entropy parameters mΔS and the Curie temperature difference [Delta] T _C It shows the ratio mΔS _maximum / [Delta] T _C and,
The magnetocaloric cascade according to claim 1 or 2. The hot-side outer layer or the low-temperature side outer layer, compared to either of the inner layer show a ratio mΔS _maximum / [Delta] T _C of at least 1% greater amount, magnetocaloric cascade according to claim 4. One of the hot-side and cold-side outer layer, and the other has a specific mΔS _maximum / [Delta] T _C of an amount greater than the other of the high temperature side and low temperature side outer layer, the ratio mΔS _largest amount greater than any of the inner layer / has a [Delta] T _C, magnetocaloric cascade according to claim 4. The hot-side layer or the low-temperature side layer, compared to either the inner layer, shows a [Delta] T _C of smaller quantities, magnetocaloric cascade according to claim 4. The hot-side layer or the low-temperature side layer indicates the amount of [Delta] T _C is not less than 0.5 K, magnetocaloric cascade according to claim 7.   The high temperature side outer layer, or the low temperature side outer layer, or both the high temperature side outer layer and the low temperature side outer layer, respectively, include at least two high temperature side sublayers or a continuous low layer of low temperature side sublayers, respectively. 9. A magnetocaloric cascade according to at least one of claims 1 to 8.   A magnetocaloric regenerator according to at least one of claims 1 to 9.   A heat pump comprising the magnetocaloric regenerator according to claim 10. -A high temperature side interface for heat exchange with the high temperature side outer layer;
A low temperature side interface that exchanges heat with the low temperature side outer layer, and a heat transfer system configured to provide a flow of heat transfer fluid between the high temperature side interface and the low temperature side interface via a magnetocaloric cascade. Because
The Curie temperature of the high temperature side outer layer is selected to be higher than the temperature of the high temperature side interface during the heat pump operation, or the Curie temperature of the low temperature side outer layer is lower than the temperature of the low temperature side interface during the heat pump operation. The heat pump of claim 11, further comprising a heat transfer system selected to be. - different a Curie temperature T _C to produce different consecutive magnetocaloric material layer having a step, the magnetocaloric material layer, the low-temperature side outer, high-temperature-side outer layer and between the high temperature side outer and the low temperature side outer Including at least three inner layers in between;
-Producing at least two of the inner layers having different masses m,
-For each pair of adjacent magnetocaloric material layers of the magnetocaloric cascade, there is a respective crossing temperature, where the pumping capacity entropy parameter mΔS of both each adjacent magnetocaloric material layer takes the same crossing point value and entropy The parameter mΔS is defined as the product of the mass m of each magnetocaloric material layer and the isothermal magnetic entropy change ΔS during the magnetic phase transition of each magnetocaloric material layer,
Furthermore,
All intersection values of the entropy parameter mΔS in all pairs of adjacent inner layers are exactly equal to the average value of all intersection values in all pairs of adjacent inner layers of the magnetocaloric cascade or range of ± 15% width In
And a magnetocaloric cascade manufacturing method. A heat pumping method comprising the step of performing a heat pumping sequence using a magnetocaloric regenerator comprising a magnetocaloric cascade according to claim 1. The heat pumping sequence includes a temperature rise of the magnetocaloric regenerator, and the heat pumping sequence is in heat exchange with a heat sink operating at a temperature 0.5K-5K higher than the Curie temperature of the high temperature side outer layer. Executed,
The heat pumping method according to claim 14.

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